virtio, vhost: fixes

ARM DMA fixes
 vhost vsock bugfix
 
 Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull virtio/vhost fixes from Michael Tsirkin:

 - ARM DMA fixes

 - vhost vsock bugfix

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  vring: Force use of DMA API for ARM-based systems with legacy devices
  virtio_mmio: Set DMA masks appropriately
  vhost/vsock: handle vhost_vq_init_access() error

drivers/vhost/vsock.c

@@ -373,6 +373,7 @@ static void vhost_vsock_handle_rx_kick(struct vhost_work *work)
 
 static int vhost_vsock_start(struct vhost_vsock *vsock)
 {
+	struct vhost_virtqueue *vq;
 	size_t i;
 	int ret;
 
@@ -383,19 +384,20 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
 		goto err;
 
 	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
-		struct vhost_virtqueue *vq = &vsock->vqs[i];
+		vq = &vsock->vqs[i];
 
 		mutex_lock(&vq->mutex);
 
 		if (!vhost_vq_access_ok(vq)) {
 			ret = -EFAULT;
-			mutex_unlock(&vq->mutex);
 			goto err_vq;
 		}
 
 		if (!vq->private_data) {
 			vq->private_data = vsock;
-			vhost_vq_init_access(vq);
+			ret = vhost_vq_init_access(vq);
+			if (ret)
+				goto err_vq;
 		}
 
 		mutex_unlock(&vq->mutex);
@@ -405,8 +407,11 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
 	return 0;
 
 err_vq:
+	vq->private_data = NULL;
+	mutex_unlock(&vq->mutex);
+
 	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
-		struct vhost_virtqueue *vq = &vsock->vqs[i];
+		vq = &vsock->vqs[i];
 
 		mutex_lock(&vq->mutex);
 		vq->private_data = NULL;

drivers/virtio/virtio_mmio.c

@@ -59,6 +59,7 @@
 #define pr_fmt(fmt) "virtio-mmio: " fmt
 
 #include <linux/acpi.h>
+#include <linux/dma-mapping.h>
 #include <linux/highmem.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
@@ -498,6 +499,7 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	struct virtio_mmio_device *vm_dev;
 	struct resource *mem;
 	unsigned long magic;
+	int rc;
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!mem)
@@ -547,9 +549,25 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	}
 	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
 
-	if (vm_dev->version == 1)
+	if (vm_dev->version == 1) {
 		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
 
+		rc = dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
+		/*
+		 * In the legacy case, ensure our coherently-allocated virtio
+		 * ring will be at an address expressable as a 32-bit PFN.
+		 */
+		if (!rc)
+			dma_set_coherent_mask(&pdev->dev,
+					      DMA_BIT_MASK(32 + PAGE_SHIFT));
+	} else {
+		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+	}
+	if (rc)
+		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
+	if (rc)
+		dev_warn(&pdev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
+
 	platform_set_drvdata(pdev, vm_dev);
 
 	return register_virtio_device(&vm_dev->vdev);

drivers/virtio/virtio_ring.c

@@ -159,6 +159,13 @@ static bool vring_use_dma_api(struct virtio_device *vdev)
 	if (xen_domain())
 		return true;
 
+	/*
+	 * On ARM-based machines, the DMA ops will do the right thing,
+	 * so always use them with legacy devices.
+	 */
+	if (IS_ENABLED(CONFIG_ARM) || IS_ENABLED(CONFIG_ARM64))
+		return !virtio_has_feature(vdev, VIRTIO_F_VERSION_1);
+
 	return false;
 }